Editing Elasmobranchii (section)

{{Short description|Subclass of fishes}}
{{Automatic taxobox
| name = Elasmobranchs
| image = Great White Shark (14730719119).jpg
| image_caption = [[Great white shark|Great white shark<br />(''Carcharodon carcharias'')]]
| fossil_range = {{Fossil range|Givetian|Recent}}
| taxon = Elasmobranchii
| authority = [[Charles Lucien Jules Laurent Bonaparte|Bonaparte]], 1838
| subdivision_ranks = Subgroups
| subdivision = [[Elasmobranchii#Taxonomy|See text]]
}}

'''Elasmobranchii''' ({{IPAc-en|ᵻ|ˌ|l|æ|z|m|ə|ˈ|b|r|æ|ŋ|k|i|aɪ}}{{refn|{{MerriamWebsterDictionary|Elasmobranch}}}}) is a [[Class (biology)|subclass]] of [[Chondrichthyes]] or cartilaginous fish, including modern [[shark]]s ([[Division (taxonomy)|division]] Selachii), and [[Batomorphi|batomorphs]] (division Batomorphi, including [[Batoidea|rays]], [[skate (fish)|skates]], and [[sawfish]]). Members of this subclass are characterised by having five to seven pairs of [[gill slit]]s opening individually to the exterior, rigid [[dorsal fin]]s and small [[placoid scale]]s on the skin. The teeth are in several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The details of this jaw anatomy vary between species, and help distinguish the different elasmobranch [[clade]]s. The pelvic fins in males are modified to create [[clasper]]s for the transfer of sperm. There is no swim bladder; instead, these fish maintain buoyancy with large livers rich in oil.

The definition of the clade is unclear with respect to fossil chondrichthyans. Some authors consider it as equivalent to '''Neoselachii''' (the [[crown group]] clade including modern sharks, rays, and all other descendants of their [[Most recent common ancestor|last common ancestor]]). Other authors use the name Elasmobranchii for a broader [[Branch-based taxon|branch-based group]] of all chondrichthyans more closely related to modern sharks and rays than to [[Holocephali]] (the clade containing [[chimaera]]s and their extinct relatives).<ref name=":1">{{Cite journal |last=Maisey |first=J. G. |date=April 2012 |title=What is an 'elasmobranch'? The impact of palaeontology in understanding elasmobranch phylogeny and evolution |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1095-8649.2012.03245.x |journal=Journal of Fish Biology |language=en |volume=80 |issue=5 |pages=918–951 |doi=10.1111/j.1095-8649.2012.03245.x|pmid=22497368 |bibcode=2012JFBio..80..918M |url-access=subscription }}</ref> Important extinct groups of elasmobranchs ''[[sensu lato]]'' include the [[hybodonts]] (Order Hybodontiformes), [[Xenacanthida|xenacanths]] (order Xenacanthformes) and [[Ctenacanthiformes]]. These are also often referred to as "sharks" in reference to their similar anatomy and ecology to modern sharks.

The name Elasmobranchii comes from the [[Ancient Greek]] words {{Transliteration|grc|elasmo-}} ("plate") and {{Transliteration|grc|bránchia}} ("gill"), referring to the broad, flattened gills which are characteristic of these fishes.

{{Quote box
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 |quote = [[File:Cetorhinus maximus by greg skomal.JPG|220px|center]] Elasmobranchs lack [[swim bladder]]s, and maintain buoyancy with oil that they store in their livers. Some deep sea sharks are targeted by fisheries for this [[Shark liver oil|liver oil]], including the [[school shark|school]], [[gulper shark|gulper]] and [[basking shark]]s ''(pictured)''.<ref name=Vannuccini2002>Vannuccini, Stefania (2002) [http://www.fao.org/docrep/005/x3690e/x3690e0r.htm Shark liver oil products] {{Webarchive|url=https://web.archive.org/web/20130626203527/http://www.fao.org/docrep/005/x3690e/x3690e0r.htm |date=2013-06-26 }} In: ''Shark Utilization, Marketing and Trade'', Fisheries Technical paper 389, FAO, Rome. {{ISBN|92-5-104361-2}}.</ref> All three of these species have been assessed by the [[IUCN]] as [[vulnerable species|vulnerable]] due to [[overfishing]].<ref name="iucn1">{{Cite iucn | author = Fowler, S.L. | title = ''Cetorhinus maximus'' | volume = 2005 | page = e.T4292A10763893 | date = 2005 | doi = 10.2305/IUCN.UK.2005.RLTS.T4292A10763893.en }}</ref><ref name="iucn2">{{cite iucn |author=Walker, T.I. |author2=Rigby, C.L. |author3=Pacoureau, N. |author4=Ellis, J. |author5=Kulka, D.W. |author6=Chiaramonte, G.E. |author7=Herman, K. |date=2020 |title=''Galeorhinus galeus'' |volume=2020 |page=e.T39352A2907336 |doi=10.2305/IUCN.UK.2020-2.RLTS.T39352A2907336.en |access-date=11 November 2021}}{{Dead link|date=December 2019 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name="iucn3">{{cite iucn |author=Finucci, B. |author2=Bineesh, K.K. |author3=Cheok, J. |author4=Cotton, C.F. |author5=Dharmadi, Kulka, D.W. |author6=Neat, F.C. |author7=Pacoureau, N. |author8=Rigby, C.L. |author9=Tanaka, S. |author10=Walker, T.I. |date=2020 |title=''Centrophorus granulosus'' |volume=2020 |page=e.T162293947A2897883 |doi=10.2305/IUCN.UK.2020-3.RLTS.T162293947A2897883.en |access-date=11 November 2021}}</ref>
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 |quote = From a practical point of view the life-history pattern of elasmobranchs makes this group of animals extremely susceptible to over fishing. It is no coincidence that the commercially exploited marine turtles and baleen whales, which have life-history patterns similar to the sharks, are also in trouble.<ref name=Hoenig1990 />
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